Display apparatus, display system having the same, and image display method thereof

ABSTRACT

The present application discloses a display apparatus including an image display portion for displaying an image, the image display portion emitting display light along a light propagating direction; and a light modulator assembly having a first light modulator and a second light modulator arranged in series along the light propagating direction. The second light modulator has at least a reflective optical state. The first light modulator is switchable between the reflective optical state and a transmissive optical state and is on a side of the second light modulator proximal to the image display portion. A total number of light modulators including the second light modulator and any light modulator on a side of the second light modulator proximal to the image display portion is N, N is an integer≥2.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a divisional of U.S. application Ser. No.15/513,270, filed Aug. 26, 2016, which is a national stage applicationunder 35 U.S.C. § 371 of International Application No.PCT/CN2016/096853, filed Aug. 26, 2016, which claims priority to ChinesePatent Application No. 201610159242.4, filed Mar. 18, 2016. Each of theforgoing applications is herein incorporated by reference in itsentirety for all purposes.

TECHNICAL FIELD

The present invention relates to a display apparatus, a display systemhaving the same, and an image display method thereof.

BACKGROUND

In recent years, development of wearable devices has become a focus ofresearch in display technology. Various types of wearable devices havebeen introduced. Among them, smart glasses have been receiving attentionby consumers. Smart glasses are sometimes called head-mounted displays.For example, Google glasses display a camera input on lens of theglasses, and combine augmented reality with an image photographed by acamera.

SUMMARY

In some embodiments, the present invention provides a display apparatuscomprising an image display portion for displaying an image, the imagedisplay portion emitting display light along a light propagatingdirection; and a light modulator assembly comprising a first lightmodulator and a second light modulator arranged in series along thelight propagating direction; the second light modulator having at leasta reflective optical state; and the first light modulator beingswitchable between the reflective optical state and a transmissiveoptical state and being on a side of the second light modulator proximalto the image display portion; a total number of light modulatorsincluding the second light modulator and any light modulator on a sideof the second light modulator proximal to the image display portion isN, N is an integer≥2.

Optionally, the N light modulators comprise N liquid crystal panels,each of the N liquid crystal panels comprises a first polarizer, a firsttransparent electrode, a liquid crystal layer, a second transparentelectrode and a second polarizer laminated in order; the secondpolarizer is a reflective polarizer disposed on a side of the firstpolarizer distal to the image display portion.

Optionally, the first polarizer has a first transmission axis, thesecond polarizer has a second transmission axis, the first transmissionaxis being substantially perpendicular to the second transmission axis;a direction of a long axis of liquid crystal molecules in the liquidcrystal layer is spirally twisted by approximately 90 degrees betweenthe first transparent electrode and the second transparent electrodeabsent of electric field; and a direction of a long axis of liquidcrystal molecules proximal to the first transparent electrode issubstantially parallel to the first transmission axis, and a directionof a long axis of liquid crystal molecules proximal to the secondtransparent electrode is substantially parallel to the secondtransmission axis, absent of electric field. the first polarizer has afirst transmission axis, the second polarizer has a second transmissionaxis, the first transmission axis being substantially parallel to thesecond transmission axis; and a long axis of liquid crystal molecules inthe liquid crystal layer is substantially parallel to the firsttransmission axis and the second transmission axis.

Optionally, the light modulator assembly comprises a plurality of curvedliquid crystal panels concave toward the image display portion; at leastone of the plurality of curved liquid crystal panels has a first lightfocus point substantially coincident with a first view region; and atleast one of the plurality of curved liquid crystal panels has a secondlight focus point substantially coincident with a second view region;the second view region different from the first view region.

Optionally, the N light modulators comprise N micro-electromechanicalsystems (MEMSs), each of the N MEMSs comprises a plurality of rotatablereflectors.

Optionally, the plurality of rotatable reflectors of a MEMS have asubstantially the same tilt angle with respect to the light propagatingdirection when the MEMS is in the reflective optical state.

Optionally, the light modulator assembly comprises a plurality of MEMSs,at least a first one of the plurality of MEMSs has a first light focuspoint substantially coincident with a first view region; and at least asecond one of the plurality of MEMSs has a second light focus pointsubstantially coincident with a second view region; the second viewregion being different from the first view region.

Optionally, the light modulator assembly comprises a plurality of MEMSs,each of the plurality of MEMSs comprises an array of rotatablereflectors corresponding to an array of pixels in the image displayportion; reflectors in odd columns of the array of rotatable reflectorshas a first light focus point substantially coincident with a first viewregion; and reflectors in even columns of the array of rotatablereflectors has a second light focus point substantially coincident witha second view region; the second view region being different from thefirst view region.

In another aspect, the present invention provides an image displaymethod using a display apparatus described herein, comprising separatinga frame of image into N sub-images; dividing a frame time period into Ntime windows corresponding to the N sub-images, respectively; andconfiguring the N light modulators so that a y-th light modulator is inthe reflective optical state in a x-th time window, and any lightmodulator on a side of the y-th light modulator proximal to the imagedisplay portion is in the transmissive optical state; wherein N is aninteger≥2; x is an integer, 1≤x≤N; y is an integer, 1≤y≤N; and y=1 forthe light modulator most proximal to the image display portion.

Optionally, the light modulator assembly is configured so thatsubstantially no more than one light modulator reflects the displaylight at a time.

Optionally, the step of separating the frame of image into N sub-imagescomprises separating the frame of image into N sub-images along a widthdirection of the frame of image.

Optionally, the step of separating the frame of image into N sub-imagescomprises separating the frame of image into a first sub-imagecorresponding to a first view region and a second sub-imagecorresponding to a second view region.

Optionally, the step of separating the frame of image into N sub-imagescomprises separating the frame of image into N portions along a widthdirection of the frame of image; and further separating each of the Nportions into a first sub-image corresponding to a first view region anda second sub-image corresponding to a second view region.

Optionally, the step of configuring the N light modulators comprisesconfiguring the N light modulator so that the y-th light modulator is inthe reflective optical state when a j-th sub-image is displayed in thex-th time window, y equals to N−j+1, j is an integer, and 1≤j≤N.

Optionally, the N light modulators comprise N liquid crystal panels,each of the N liquid crystal panels comprises a first polarizer, a firsttransparent electrode, a liquid crystal layer, a second transparentelectrode and a second polarizer laminated in order; the secondpolarizer is a reflective polarizer disposed on a side of the firstpolarizer distal to the image display portion; and the step ofconfiguring the N light modulators comprises controlling an electricfield between the first transparent electrode and the second transparentelectrode.

Optionally, the first polarizer has a first transmission axis, thesecond polarizer has a second transmission axis, the first transmissionaxis being substantially perpendicular to the second transmission axis;a direction of a long axis of liquid crystal molecules in the liquidcrystal layer is spirally twisted by approximately 90 degrees betweenthe first transparent electrode and the second transparent electrodewhen electric field is not applied; and a direction of a long axis ofliquid crystal molecules proximal to the first transparent electrode issubstantially parallel to the first transmission axis, and a directionof a long axis of liquid crystal molecules proximal to the secondtransparent electrode is substantially parallel to the secondtransmission axis, when electric field is not applied; each of the Nliquid crystal panels is in the reflective optical state when there isno electric field between the first transparent electrode and the secondtransparent electrode; each of the N liquid crystal panels is in thetransmissive optical state when a strength of the electric field islarger than a threshold value.

Optionally, the first polarizer has a first transmission axis, thesecond polarizer has a second transmission axis, the first transmissionaxis being substantially parallel to the second transmission axis; and along axis of liquid crystal molecules in the liquid crystal layer issubstantially parallel to the first transmission axis and the secondtransmission axis.

Optionally, the N light modulators comprise N MEMSs, each of the N MEMSscomprises a plurality of rotatable reflectors; and the step ofconfiguring the N light modulators comprises rotating the plurality ofrotatable reflectors of a MEMS to change tilt angles of the plurality ofrotatable reflectors.

Optionally, the plurality of rotatable reflectors of the MEMS arerotated to have a substantially the same tilt angle with respect to thelight propagating direction so that the MEMS is in the reflectiveoptical state; the display light reflected by the plurality of rotatablereflectors has a substantially the same propagating direction.

Optionally, the light modulator assembly comprises a plurality of MEMSs,a plurality of rotatable reflectors of at least a first one of theplurality of MEMSs are rotated to have a first light focus pointsubstantially coincident with a first view region; and a plurality ofrotatable reflectors of at least a second one of the plurality of MEMSsare rotated to have a second light focus point substantially coincidentwith a second view region; the second view region being different fromthe first view region.

Optionally, the light modulator assembly comprises a plurality of MEMSs,each of the plurality of MEMSs comprises an array of rotatablereflectors corresponding to an array of pixels in the image displayportion; reflectors in odd columns of the array of rotatable reflectorsare rotated to have a first light focus point substantially coincidentwith a first view region; and reflectors in even columns of the array ofrotatable reflectors are rotated to have a second light focus pointsubstantially coincident with a second view region; the second viewregion being different from the first view region.

Optionally, the method further comprises enhancing brightness of atleast one of the N sub-images so that sub-images displayed in lightmodulators distal to the image display portion have a higher brightnessthan sub-images displayed in light modulators proximal to the imagedisplay portion.

BRIEF DESCRIPTION OF THE FIGURES

The following drawings are merely examples for illustrative purposesaccording to various disclosed embodiments and are not intended to limitthe scope of the present invention.

FIG. 1 is a diagram illustrating the structure of a display apparatus insome embodiments.

FIG. 2 is a diagram illustrating a smart glasses system in someembodiments.

FIG. 3 is a diagram illustrating the structure of a liquid crystal panelin some embodiments.

FIG. 4 is a diagram illustrating the structure of a liquid crystal panelin some embodiments.

FIG. 5 is a diagram illustrating the structure of a liquid crystal panelin some embodiments.

FIG. 6 is a diagram illustrating the structure of a display apparatus insome embodiments.

FIG. 7 is a diagram illustrating the structure of a display apparatus insome embodiments.

FIG. 8 is a diagram illustrating the structure of a display apparatus insome embodiments.

FIG. 9 is a diagram illustrating the structure of a display apparatus insome embodiments.

FIG. 10 is a diagram illustrating the structure of a display apparatusin some embodiments.

FIG. 11 is a diagram illustrating the structure of a display apparatusin some embodiments.

FIG. 12 is a diagram illustrating the structure of a display apparatusin some embodiments.

FIG. 13 is a diagram illustrating a tilt angle of a reflector withrespect to the light propagating direction in some embodiments.

FIG. 14 is a diagram illustrating separation of a frame of image intomultiple sub-images in some embodiments.

FIG. 15 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 16 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 17 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 18 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 19 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 20 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 21 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

FIG. 22 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments.

DETAILED DESCRIPTION

The disclosure will now describe more specifically with reference to thefollowing embodiments. It is to be noted that the following descriptionsof some embodiments are presented herein for purpose of illustration anddescription only. It is not intended to be exhaustive or to be limitedto the precise form disclosed.

Conventional smart glasses systems typically include an image displaymodule and an image conversion module for image display. In theconventional smart glasses systems, both the image display module andthe image conversion module have a width larger than a width of adisplayed image in order to display a complete frame of image. Limitedby this requirement, the conventional smart glasses systems typicallyhave a large thickness. Miniaturized designs are difficult to beimplemented in such conventional smart glasses systems.

The present disclosure provides a display apparatus, a display systemhaving the same, and an image display method thereof that substantiallyobviate one or more of the problems due to limitations and disadvantagesof the related art. In some embodiments, the present display apparatusincludes an image display portion for displaying an image, the imagedisplay portion emitting display light along a light propagatingdirection; and a light modulator assembly including a first lightmodulator and a second light modulator arranged in series along thelight propagating direction. The second light modulator has at least areflective optical state. The first light modulator is switchablebetween the reflective optical state and a transmissive optical state,and is on a side of the second light modulator proximal to the imagedisplay portion. A total number of light modulators including the secondlight modulator and any light modulator on a side of the second lightmodulator proximal to the image display portion is N, N is an integer≥2.Optionally, any light modulator on a side of the second light modulatorproximal to the image display portion is switchable between thereflective optical state and a transmissive optical state.

Optionally, the present display apparatus includes an image displayportion for displaying an image; the image display portion emittingdisplay light along a light propagating direction; and a light modulatorassembly including N light modulators arranged in series along the lightpropagating direction; N is an integer≥2; a light modulator most distalto the image display portion having a reflective optical state; and allother light modulators being switchable between a reflective opticalstate and a transmissive optical state.

In some embodiments, the present image display method includesseparating a frame of image into N sub-images; dividing a frame timeperiod into N time windows corresponding to the N sub-images,respectively; and configuring the N light modulators so that a y-thlight modulator is in the reflective optical state in a x-th timewindow, and any light modulator on a side of the y-th light modulatorproximal to the image display portion is in the transmissive opticalstate; wherein N is an integer≥2; x is an integer, 1≤x≤N; y is aninteger, 1≤y≤N; and y=1 for the light modulator most proximal to theimage display portion.

As used herein, the term “transmissive optical state” in the context ofa light modulator means that the light modulator is in a state thatallows incident light to pass through. As used herein, the term“reflective optical state” in the context of a light modulator meansthat the light modulator is in a state that reflects incident light. Asused herein, the term “light modulator” refers to a device that receiveslight and is capable of controlling the flow or characteristics of lightsuch as the direction, a degree of transmission or reflection, etc.Optionally, when a light modulator is in a transmissive optical state,it substantially does not reflect incident light, i.e., the lightmodulator is substantially transmissive. Optionally, when a lightmodulator is in a reflective optical state, it substantially does notallow incident light to pass through, i.e., the light modulator issubstantially reflective. Optionally, the light modulator's modulationon the incident light is substantially wavelength-independent (e.g., itdoes not selectively reflect specific wavelengths of the incident lightwhile passing other wavelengths of the incident light). Optionally, thelight modulator's modulation on the incident light is not based on Braggselectivity. Optionally, when a light modulator is in a reflectiveoptical state, light reflected by the light modulator has asubstantially the same wavelength as the incident light.

FIG. 1 is a diagram illustrating a displaying sequence of multiplesub-images in some embodiments. Referring to FIG. 1, the displayapparatus in the embodiment includes an image display portion 1 fordisplaying an image, and a light modulator assembly 2. As shown in FIG.2, the image display portion 1 emits display light L along a lightpropagating direction P. The light modulator assembly 2 includes N lightmodulators 21 arranged in series along the light propagating direction P(distal to light emitting surface of the image display portion 1). N isan integer≥2. In some embodiments, the light modulator 21 has one ormore of optical states selected from a reflective optical state and atransmissive optical state. Optionally, a light modulator 21 most distalto the image display portion (the light modulator 21 on the left side ofFIG. 1) has a reflective optical state, and all other light modulators21 are switchable between a reflective optical state and a transmissiveoptical state. Optionally, the light modulator 21 most distal to theimage display portion is also switchable between a reflective opticalstate and a transmissive optical state. Optionally, the light modulator21 most distal to the image display portion has only one optical state,i.e., the reflective optical state. When a light modulator 21 isswitchable between a reflective optical state and a transmissive opticalstate, the switching process is reversible, i.e., the light modulator 21is reversibly switchable between the reflective optical state and thetransmissive optical state. Optionally, 2≤N≤5.

In some embodiments, the display apparatus is a smart glasses system(see, e.g., the smart glasses system as shown in FIG. 2). The smartglasses system includes an image display portion, a light modulatorassembly, as well as a frame and lenses. In some embodiments, thedisplay apparatus is a hand-held display apparatus, a household displayapparatus, or an outdoor display apparatus. Examples of appropriatedisplay apparatuses include, but are not limited to, a television, amonitor, and a gaming system. The present display apparatus has theadvantages of having a smaller size and being energy efficient.

Various appropriate image display portions may be used for making thepresent display apparatus. Examples of image display portions include,but are not limited to, a light emitting diode (LED) display module, anorganic light emitting display (OLED) module, a quantum dot displaymodule, and a laser scan display module.

By having a light modulator assembly including N light modulators (N isan integer≥2) in the present display apparatus, a frame of image may beseparated into N sub-images during image display, and a frame timeperiod may be divided into N time windows corresponding to the Nsub-images. Accordingly, each of the N sub-images may be displayed in adifferent time window. For example, when the x-th sub-image isdisplayed, a light modulator corresponding to the x-th sub-image isconfigured to be in a reflective optical state, whereas any lightmodulator on a side of the light modulator for displaying the x-thsub-image proximal to the image display portion is configured to be in atransmissive optical state. For example, any light modulator in a lightpath between the image display portion and the light modulator fordisplaying the x-th sub-image is configured to be is a transmissiveoptical state so that the display light may pass through from the imagedisplay portion to the light modulator for displaying the x-thsub-image, and the display light is reflected by the light modulator fordisplaying the x-th sub-image to an eye or a view point. Each of the Nsub-images are displayed in a time window. Due to persistence of vision,human eyes can perceive a complete frame of image when a set ofsub-images are displayed in quick succession. Accordingly, in someembodiments, a frame of image may be separated into N sub-images along awidth direction of the frame of image. As a result, image display of acomplete frame of image may be achieved by using an image displayportion having a width corresponding to only a width of one sub-image(rather than the width of an entire frame of image). By having thisdesign, the thickness of the image display portion may be reduced,resulting in a miniaturized display apparatus.

Various appropriate light modulators may be used for making the presentdisplay apparatus. Examples of appropriate light modulators include, butare not limited to, electro-optic type light modulators (e.g., liquidcrystal), electromechanical type light modulators, electrochromic typelight modulators, and other types of light modulators such as aplansmonic nano-antenna (see, e.g., U.S. Pat. No. 9,285,611, thecontents of which are incorporated herein by reference in its entirety).In some embodiments, light modulators include liquid crystal panels andmicro-electromechanical system (MEMS). Examples of liquid crystal panelsinclude a liquid crystal on silicon (LCOS) using ferroelectric liquidcrystals. Examples of MEMSs include micro mirror array systems such as adigital micro-mirror device. These light modulators modulate light bydigitally switching ON and OFF light. Optionally, the light modulator isa reflective light modulator that does not have a transmissive opticalstate (e.g., a light modulator most distal to the image displayportion). Examples of reflective light modulator further includereflective thin film transistor based liquid crystal display.

Optionally, the light modulator assembly includes N light modulators ofa same type and having a substantially the same structure. Optionally,different types of light modulators may be used in the light modulatorassembly.

In some embodiments, the light modulator is a liquid crystal panel. FIG.3 is a diagram illustrating the structure of a liquid crystal panel insome embodiments. FIG. 4 is a diagram illustrating the structure of aliquid crystal panel in some embodiments. Referring to FIG. 3 and FIG.4, the liquid crystal panels in the embodiments include a firstpolarizer 211, a first transparent electrode 212, a liquid crystal layer213, a second transparent electrode 214 and a second polarizer 215laminated in order; the second polarizer 215 is a reflective polarizerdisposed on a side of the first polarizer 211 distal to the imagedisplay portion. The reflective polarizer 215 is a polarizer that iscapable of reflecting light having a polarization directionperpendicular to a transmission axis of the reflective polarizer 215.Optionally, the reflective polarizer 215 is made by forming a reflectivelayer on a polarizer. Optionally, the first transparent electrode 212and the second transparent electrode 214 are both plate electrodes,obviating a need for patterning the first transparent electrode 212 andthe second transparent electrode 214 and simplifying the fabricatingprocess of the liquid crystal panel.

Various embodiments of liquid crystal panels capable of switchingbetween a reflective optical state and a transmissive optical state maybe use for making the present display apparatus. Similarly, thetransmission axes of the first polarizer and the second polarizer in theliquid crystal panel may have various relative orientation to achievebi-optical states or an intermediate optical state. Accordingly, liquidcrystal molecules in the liquid crystal layer have various initialorientation depending on the relative orientation of the transmissionaxes.

In some embodiments, the first polarizer has a first transmission axis,the second polarizer has a second transmission axis, the firsttransmission axis is substantially perpendicular to the secondtransmission axis. Optionally, a direction of a long axis of liquidcrystal molecules in the liquid crystal layer is spirally twisted byapproximately 90 degrees between the first transparent electrode and thesecond transparent electrode when electric field is not applied. Asshown in FIG. 3, the first polarizer 211 has a first transmission axisA1, the second polarizer has a second transmission axis A2, A1 and A2being substantially perpendicular to each other. When an electric fieldis not applied between the first transparent electrode 212 and thesecond transparent electrode 214, a direction of a long axis of liquidcrystal molecules proximal to the first transparent electrode 212(annotated as “L1” in FIG. 3) is substantially parallel to the firsttransmission axis A1, and a direction of a long axis of liquid crystalmolecules proximal to the second transparent electrode 214 (annotated as“L2” in FIG. 3) is substantially parallel to the second transmissionaxis A2.

When an electric field is not applied between the first transparentelectrode 212 and the second transparent electrode 214, the liquidcrystal molecules in the liquid crystal layer 213 maintain an initialorientation as shown in FIG. 3. The display light emitted from the imagedisplay portion includes a component having a polarization directionsubstantially parallel to the transmission axis A1, which is capable ofpassing through the first polarizer 211. The light passing through thefirst polarizer 211 travels through the liquid crystal layer 213, duringwhich the polarization direction of the light is rotated by 90 degrees.As a result, the rotated polarization direction becomes substantiallyparallel to the transmission axis A2 of the second polarizer 215, andthe light passed through the second polarizer 215. In this embodiment,the liquid crystal panel is in a transmissive optical state.

When an electric field is applied between the first transparentelectrode 212 and the second transparent electrode 214, the liquidcrystal molecules in the liquid crystal layer 213 reorient so that thelong axis of liquid crystal molecules has a different orientation. Insome embodiments, a strength of the electric field between the firsttransparent electrode 212 and the second transparent electrode 214exceeds a threshold value, the long axis of substantially all liquidcrystal molecules in the liquid crystal layer 213 is arranged to besubstantially perpendicular to the first transparent electrode 211. Thecomponent of the display light emitted from the image display portionhaving a polarization direction parallel to the transmission axis A1 ofthe first polarizer 211 passes through the first polarizer 211. Thelight passing through the first polarizer 211 continues to travelthrough the liquid crystal layer 213, maintaining its polarizationdirection unchanged. When the light reaches the second polarizer 215,the polarization direction of the light is substantially perpendicularto the transmission axis A2 of the second polarizer 215. Because thesecond polarizer 215 is a reflective polarizer, the light is reflectedby the second polarizer 215. The reflected light travels through theliquid crystal layer 213 (in a reversed direction), again maintaining itpolarization direction unchanged, and emits out of the first polarizer211. In this embodiment, the liquid crystal panel is in a reflectiveoptical state. The threshold value of the strength of the electric fieldbetween the first transparent electrode 212 and the second transparentelectrode 214 may be determined based on several factors, e.g., thechemical and physical properties of the liquid crystal molecules, thedistance between the first transparent electrode 212 and the secondtransparent electrode 214.

In some embodiments, the first polarizer has a first transmission axis,the second polarizer has a second transmission axis, and the firsttransmission axis is substantially parallel to the second transmissionaxis. Optionally, a long axis of substantially all liquid crystalmolecules in the liquid crystal layer is substantially parallel to thefirst transmission axis and the second transmission axis. As shown inFIG. 4, the first polarizer 211 has a first transmission axis A1, thesecond polarizer has a second transmission axis A2, A1 and A2 beingsubstantially parallel to each other. When an electric field is notapplied between the first transparent electrode 212 and the secondtransparent electrode 214, a direction of a long axis of substantiallyall liquid crystal molecules in the liquid crystal layer 213 (see, e.g.,the long axis L1 of liquid crystal molecules proximal to the firsttransparent electrode 212 and the long axis L2 of liquid crystalmolecules proximal to the second transparent electrode 214) issubstantially parallel to A1 and A2.

When an electric field is not applied between the first transparentelectrode 212 and the second transparent electrode 214, the liquidcrystal molecules in the liquid crystal layer 213 maintain an initialorientation as shown in FIG. 4. The display light emitted from the imagedisplay portion includes a component having a polarization directionsubstantially parallel to the transmission axis A1, which is capable ofpassing through the first polarizer 211. The light passing through thefirst polarizer 211 travels through the liquid crystal layer 213, duringwhich the polarization direction of the light is substantiallymaintained unchanged. When the light reaches the second polarizer 215,the polarization direction of the light is substantially parallel to thetransmission axis A2 of the second polarizer 215. As a result, the lightcontinues to pass through the second polarizer 215. In this embodiment,the liquid crystal panel is in a transmissive optical state.

When an electric field is applied between the first transparentelectrode 212 and the second transparent electrode 214, the liquidcrystal molecules in the liquid crystal layer 213 reorient so that thelong axis of liquid crystal molecules has a different orientation. Insome embodiments, a strength of the electric field between the firsttransparent electrode 212 and the second transparent electrode 214exceeds a threshold value, the long axis of substantially all liquidcrystal molecules in the liquid crystal layer 213 is arranged to besubstantially perpendicular to the first transparent electrode 211. Thecomponent of the display light emitted from the image display portionhaving a polarization direction parallel to the transmission axis A1 ofthe first polarizer 211 passes through the first polarizer 211. Thelight passing through the first polarizer 211 continues to travelthrough the liquid crystal layer 213, during which the polarizationdirection of the light is rotated by 90 degrees. When the light reachesthe second polarizer 215, the polarization direction of the light issubstantially perpendicular to the transmission axis A2 of the secondpolarizer 215. Because the second polarizer 215 is a reflectivepolarizer, the light is reflected by the second polarizer 215. Thereflected light travels through the liquid crystal layer 213 (in areversed direction), during which the polarization direction of thelight is again rotated by 90 degrees. When the reflected light travelsback to the first polarizer 211, the polarization direction of thereflected light is substantially parallel to the transmission axis ofthe first polarizer 211, and emits out of the first polarizer 211. Inthis embodiment, the liquid crystal panel is in a reflective opticalstate. The threshold value of the strength of the electric field betweenthe first transparent electrode 212 and the second transparent electrode214 may be determined based on several factors, e.g., the chemical andphysical properties of the liquid crystal molecules, the distancebetween the first transparent electrode 212 and the second transparentelectrode 214.

In some embodiments, when an electric field is not applied between thefirst transparent electrode and the second transparent electrode, theliquid crystal panel is in a transmissive optical state (as shown inFIG. 4 and FIG. 4). In some embodiments, when an electric field isapplied between the first transparent electrode and the secondtransparent electrode, and the strength of the electric field betweenthe first transparent electrode and the second transparent electrodeexceeds a threshold value, the liquid crystal panel is in a reflectiveoptical state (as shown in FIG. 5). When these embodiments areimplemented in the present display apparatus, each light modulator isonly required to be in the reflective optical state when the lightmodulator is displaying a corresponding sub-image. In all other timewindows, the light modulator may be in the transmissive optical stateduring which the electric field is not applied to the liquid crystalpanel. Thus, the display apparatus having this design is energyefficient.

Numerous alternative structures of the liquid crystal panels may beused. For example, in some embodiments, the liquid crystal panel mayinclude a first polarizer, a first transparent plate electrode, aninsulating layer, a liquid crystal layer, a second transparent rodelectrode, and a second polarizer laminated in order. Moreover, thetransmission axes of the first polarizer and the second polarizer mayhave various relative orientation (e.g., other than perpendicular toeach other and parallel to each other). The liquid crystal molecules inthe liquid crystal layer may be designed to have various initialorientation as long as the reflective optical state and the transmissiveoptical state may be achieved in the liquid crystal panel.

Various appropriate shapes may be used for making the liquid crystalpanels. As shown in FIG. 1, the light modulator assembly 2 includes aplurality of flat liquid crystal panels having a plate shape, all ofwhich reflect light towards a substantially the same direction when theyare configured in a reflective optical state. In some embodiments, aframe of image is separated into a plurality of sub-images along thewidth direction of the frame of image, and a frame time period isdivided into a plurality of time windows corresponding to the pluralityof sub-images, respectively. Optionally, in each time window, asub-image is displayed, and the display light for display the sub-imageis reflected by the liquid crystal panel designated for displaying thesub-image. When the sub-image is displayed and the display light isreflected by the liquid crystal panel designated for the sub-image, anyliquid crystal panel on a side of the designated liquid crystal panelproximal to the image display portion is configured to be in atransmissive optical state so that the display light may pass through tothe designated liquid crystal panel. When the frame time periodcorresponding to the frame of image ends, all sub-images of the frame ofimage are displayed in multiple liquid crystal panels, a complete frameof image may be perceived by an observer (e.g., a human eye).

In some embodiments, the liquid crystal panels are curved liquid crystalpanels. FIG. 6 is a diagram illustrating the structure of a displayapparatus in some embodiments. FIG. 7 is a diagram illustrating thestructure of a display apparatus in some embodiments. Referring to FIG.6 and FIG. 7, the light modulator assemblies 2 in the embodimentsinclude a plurality of curved liquid crystal panels 21 concave towardthe image display portion 1. Optionally, the plurality of curved liquidcrystal panels 21 have difference curvature states. Optionally, theplurality of curved liquid crystal panels 21 have a substantially thesame curvature state but different tilt angles. Optionally, at least oneof the plurality of curved liquid crystal panels 21 has a first lightfocus point substantially coincident with a first view region, and atleast one of the plurality of curved liquid crystal panels 21 has asecond light focus point substantially coincident with a second viewregion; and the second view region different from the first view region.As shown in FIG. 6 and FIG. 7, the first view region (or a first viewpoint) may be a human eye (e.g., a left eye), and the second view region(or a second view point) may be another human eye (e.g., a right eye).Optionally, the first view region (or a first view point) may be a firstcamera, and the second view region (or a second view point) may be asecond camera. When the first and the second view regions correspond toa human's left and right eyes, respectively, naked eye three-dimensionaldisplay may be made possible using a miniaturized display apparatus.

Referring to FIG. 7 and FIG. 7, the light modulator assembly 2 includestwo curved liquid crystal panels 21 arranged in series along the lightpropagating direction. As shown in FIG. 6, a first liquid crystal panel21 (on the left side of the display apparatus) reflects display lightfrom the image display portion 1 to a left eye of a human when the firstliquid crystal panel 21 is configured to be in a reflective opticalstate and the second liquid crystal panel 21 is configured to be in atransmissive optical state. As shown in FIG. 7, a second liquid crystalpanel 21 reflects display light from the image display portion 1 to aright eye of a human when the second liquid crystal panel 21 isconfigured to be in a reflective optical state.

In some embodiments, a frame of image is separated into multiplesub-images each of which corresponding to a view region. For example, aframe of image may be separated into two sub-images, the first sub-imagecorresponding to a left eye of a human and the second sub-imagecorresponding to a right eye. Further, a frame time period correspondingto the frame of image is divided into a first time window and a secondtime window. In the first time window, the first sub-image is displayed.Accordingly, the first liquid crystal panel 21 is configured to be in areflective optical state and the second liquid crystal panel 21 isconfigured to be in a transmissive optical state. The display lightcorresponding to the first sub-image emits from the image displayportion 1 is reflected to the left eye (the first view region). In thesecond time window, the second sub-image is displayed. Accordingly, thesecond liquid crystal panel 21 is configured to be in a reflectiveoptical state. The display light corresponding to the second sub-imageemits from the image display portion 1 is reflected to the right eye(the second view region). When the frame time period corresponding tothe frame of image ends, the left eye perceives the first sub-image, andthe right eye perceives the second sub-image, thereby realizing thenaked eye three-dimensional display.

FIG. 8 is a diagram illustrating the structure of a display apparatus insome embodiments. Referring to FIG. 8, the light modulator assembly 2 inthe embodiment includes multiple liquid crystal panels 21 havingdifferent curvature states, i.e., a first liquid crystal panel 21, asecond liquid crystal panel 21, a third liquid crystal panel 21, and afourth liquid crystal panel 21 arranged in series along the lightpropagating direction (sequentially from left to right in FIG. 8). Thefirst liquid crystal panel 21 has a light focus point substantiallycoincident with a first view region (e.g., the left eye) when the firstliquid crystal panel 21 is configured to be in a reflective opticalstate. The second liquid crystal panel 21 has a light focus pointsubstantially coincident with the first view region (e.g., the left eye)when the second liquid crystal panel 21 is configured to be in areflective optical state. The third liquid crystal panel 21 has a lightfocus point substantially coincident with a second view region (e.g.,the right eye) when the third liquid crystal panel 21 is configured tobe in a reflective optical state. The fourth liquid crystal panel 21 hasa light focus point substantially coincident with the second view region(e.g., the right eye) when the fourth liquid crystal panel 21 isconfigured to be in a reflective optical state.

In some embodiments, a frame of image may be first separated intomultiple portions along a width direction of the frame of image, each ofwhich is then further separated into multiple sub-images. For example, aframe of image may be separated into two portions along a widthdirection of the frame of image, i.e., a first portion and a secondportion. Each of the first portion and the second portion is thenfurther separated into a first sub-image corresponding to a first viewregion (e.g., the left eye) and a second sub-image corresponding to asecond view region (e.g., the right eye). Specifically, the firstportion is further separated into a first sub-image of the first portioncorresponding to the left eye and a second sub-image of the firstportion corresponding to the right eye; and the second portion isfurther separated into a first sub-image of the second portioncorresponding to the left eye and a second sub-image of the secondportion corresponding to the right eye. Moreover, a frame time periodcorresponding to the frame of image is divided into four time windows,i.e., a first time window, a second time window, a third time window,and a fourth time window. The first sub-image and the second sub-imageof the first portion and the first sub-image and the second sub-image ofthe second portion may be displayed in the first to fourth time windowsin any appropriate order. For example, in some embodiments, the firstsub-image of the first portion corresponding to the left eye, the firstsub-image of the second portion corresponding to the left eye, thesecond sub-image of the first portion corresponding to the right eye,and the second sub-image of the second portion corresponding to theright eye, are sequentially displayed in the first to fourth time windowby the first to fourth liquid crystal panels, e.g., the display lightcorresponding to each sub-image is reflected by a designated liquidcrystal panel when the designated liquid crystal panel is configured tobe in a reflective optical state. When a designated liquid crystal panelis configured to be in a reflective optical state to reflect the displaylight for a corresponding sub-image, any liquid crystal panel on a sideof the designated liquid crystal panel proximal to the image displayportion is configured to be in a transmissive optical state. When theframe time period corresponding to the frame of image ends, the left eyeperceives the first sub-image of the first portion and the firstsub-image of the second portion, and the right eye perceives the secondsub-image of the first portion and the second sub-image of the secondportion, thereby realizing the naked eye three-dimensional display.

Numerous alternative embodiments may be practiced to implement the nakedeye three-dimensional display method described herein. For example, thelight modulator assembly may include various numbers of curved liquidcrystal panels. The curvature states of the curved liquid crystal panelsin various embodiments may be determined by experiment and simulation.

In some embodiments, the light modulators are MEMSs. FIGS. 9-12illustrate the structures of display apparatuses in various embodimentsin which the light modulators are MEMSs. Referring to FIGS. 9-12, eachMEMS include a plurality of rotatable reflectors. The rotatablereflectors (thus the MEMS) are configured to have at least two opticalstates, e.g., a reflective optical state and a transmissive opticalstate. Optionally, the rotatable reflectors are configured to be in atransmissive optical state to allow the display light passing through.Optionally, the rotatable reflectors are configured to be in areflective optical state to reflect the display light. Further, therotatable reflectors in the reflective optical state may be configuredto be rotated to different tilt angles so that the display light may bereflected along different directions.

In some embodiments, the rotatable reflectors of a MEMS are rotated tobe facing towards the image display portion, and the MEMS is configuredto be in the reflective optical state. In some embodiments, therotatable reflectors of a MEMS are rotated so that planes ofsubstantially all rotatable reflectors are substantially parallel to thelight propagating direction, and the MEMS is configured to be in thetransmissive optical state.

When the MEMS is configured to the in the reflective optical state, thedisplay light may be reflected towards different directions if therotatable reflectors of the MEMS are rotated to have different tiltangles. FIG. 13 is a diagram illustrating a tilt angle of a reflectorwith respect to the light propagating direction in some embodiments.Referring to FIG. 13, the tilt angle between a plane of the reflector(i.e., the light reflecting surface plane) and the light propagatingdirection is θ. Accordingly, the direction of the light reflected by thereflector may be adjusted by changing a tilt angle of the reflector.

Referring to FIG. 9, the light modulator assembly 2 in the embodimentincludes a plurality of MEMSs. The plurality of rotatable reflectors ofeach MEMS have a substantially the same tilt angle with respect to thelight propagating direction when the MEMS is in the reflective opticalstate. Thus, when each MEMS reflects the display light, light modulationeffects of each MEMS is substantially the same. In some embodiments, aframe of image is separated into multiple sub-images along the widthdirection of the frame of image, and a frame time period is divided intomultiple time windows corresponding to multiple sub-images,respectively, and each sub-image is displayed in each time window. Ineach time window, a sub-image is displayed, and the display light fordisplay the sub-image is reflected by a MEMS designated for displayingthe sub-image. When the sub-image is displayed and the display light isreflected by a MEMS designated for the sub-image, any MEMS on a side ofthe designated MEMS proximal to the image display portion is configuredto be in a transmissive optical state (e.g., the tilt angle is set tozero) so that the display light may pass through to the designated MEMS.When the frame time period corresponding to the frame of image ends, allsub-images of the frame of image are displayed in multiple MEMS, acomplete frame of image may be perceived by an observer (e.g., a humaneye).

In some embodiments, the light modulator assembly 2 includes a pluralityof MEMSs. Some MEMSs (e.g., at least a first one) of the light modulatorassembly 2 have a first light focus point substantially coincident witha first view region (e.g., a first view point). Some other MEMSs (e.g.,at least a second one) have a second light focus point substantiallycoincident with a second view region (e.g., a second view point). Thesecond view region is different from the first view region. When thefirst and the second view regions correspond to a human's left and righteyes, respectively, naked eye three-dimensional display may be madepossible using a miniaturized display apparatus.

Referring to FIG. 10 and FIG. 11, the light modulator assembly 2includes two MEMSs, i.e., a first MEMS and a second MEMS, arranged inseries along the light propagating direction. As shown in FIG. 10, afirst MEMS (on the left side of the display apparatus) reflects displaylight from the image display portion 1 to a left eye of a human when thefirst MEMS is configured to be in a reflective optical state and thesecond MEMS is configured to be in a transmissive optical state. Asshown in FIG. 11, a second MEMS reflects display light from the imagedisplay portion 1 to a right eye of a human when the second MEMS isconfigured to be in a reflective optical state.

In some embodiments, a frame of image is separated into multiplesub-images each of which corresponding to a view region. For example, aframe of image may be separated into two sub-images, the first sub-imagecorresponding to a left eye of a human and the second sub-imagecorresponding to a right eye. Further, a frame time period correspondingto the frame of image is divided into a first time window and a secondtime window. In the first time window, the first sub-image is displayed.Accordingly, the first MEMS is configured to be in a reflective opticalstate and the second MEMS is configured to be in a transmissive opticalstate. The display light corresponding to the first sub-image emits fromthe image display portion 1 is reflected to the left eye (the first viewregion). In the second time window, the second sub-image is displayed.Accordingly, the second MEMS is configured to be in a reflective opticalstate. The display light corresponding to the second sub-image emitsfrom the image display portion 1 is reflected to the right eye (thesecond view region). When the frame time period corresponding to theframe of image ends, the left eye perceives the first sub-image, and theright eye perceives the second sub-image, thereby realizing the nakedeye three-dimensional display.

FIG. 12 is a diagram illustrating the structure of a display apparatusin some embodiments. Referring to FIG. 12, the light modulator assembly2 in the embodiment includes multiple MEMSs, i.e., a first MEMS, asecond MEMS, a third MEMS, and a fourth MEMS arranged in series alongthe light propagating direction (sequentially from left to right in FIG.12). The first MEMS has a light focus point substantially coincidentwith a first view region (e.g., the left eye) when the first MEMS isconfigured to be in a reflective optical state. The second MEMS has alight focus point substantially coincident with the first view region(e.g., the left eye) when the second MEMS is configured to be in areflective optical state. The third MEMS has a light focus pointsubstantially coincident with a second view region (e.g., the right eye)when the third MEMS is configured to be in a reflective optical state.The fourth MEMS has a light focus point substantially coincident withthe second view region (e.g., the right eye) when the fourth MEMS isconfigured to be in a reflective optical state.

In some embodiments, a frame of image may be first separated intomultiple portions along a width direction of the frame of image, each ofwhich is then further separated into multiple sub-images. For example, aframe of image may be separated into two portions along a widthdirection of the frame of image, i.e., a first portion and a secondportion. Each of the first portion and the second portion is thenfurther separated into a first sub-image corresponding to a first viewregion (e.g., the left eye) and a second sub-image corresponding to asecond view region (e.g., the right eye). Specifically, the firstportion is further separated into a first sub-image of the first portioncorresponding to the left eye and a second sub-image of the firstportion corresponding to the right eye; and the second portion isfurther separated into a first sub-image of the second portioncorresponding to the left eye and a second sub-image of the secondportion corresponding to the right eye. Moreover, a frame time periodcorresponding to the frame of image is divided into four time windows,i.e., a first time window, a second time window, a third time window,and a fourth time window. The first sub-image and the second sub-imageof the first portion and the first sub-image and the second sub-image ofthe second portion may be displayed in the first to fourth time windowsin any appropriate order. For example, in some embodiments, the firstsub-image of the first portion corresponding to the left eye, the firstsub-image of the second portion corresponding to the left eye, thesecond sub-image of the first portion corresponding to the right eye,and the second sub-image of the second portion corresponding to theright eye, are sequentially displayed in the first to fourth time windowby the first to fourth MEMSs, e.g., the display light corresponding toeach sub-image is reflected by a designated MEMS when the designatedMEMS is configured to be in a reflective optical state. When adesignated MEMS is configured to be in a reflective optical state toreflect the display light for a corresponding sub-image, any MEMS on aside of the designated MEMS proximal to the image display portion isconfigured to be in a transmissive optical state. When the frame timeperiod corresponding to the frame of image ends, the left eye perceivesthe first sub-image of the first portion and the first sub-image of thesecond portion, and the right eye perceives the second sub-image of thefirst portion and the second sub-image of the second portion, therebyrealizing the naked eye three-dimensional display.

In some embodiments, the light modulator assembly includes a pluralityof MEMS, each of the plurality of MEMSs includes an array of rotatablereflectors corresponding to an array of pixels in the image displayportion. Optionally, reflectors in odd columns of the array of rotatablereflectors has a first focus point substantially coincident with a firstview region (e.g., a first view point). Optionally, reflectors in evencolumns of the array of rotatable reflectors has a second focus pointsubstantially coincident with a second view region (e.g., a second viewpoint), the second view region being different from the first viewregion. When the first and the second view regions correspond to ahuman's left and right eyes, respectively, naked eye three-dimensionaldisplay may be made possible using a miniaturized display apparatus.Optionally, a column direction of the array of rotatable reflectors issubstantially parallel to a column direction of the array of pixels inthe image display portion.

In some embodiments, the light modulator assembly includes two MEMSarranged in series along the light propagating direction, e.g., a firstMEMS and a second MEMS, each of which includes an array of rotatablereflectors corresponding to an array of pixels in the image displayportion. In each of the first MEMS and the second MEMS, reflectors inodd columns of the array of rotatable reflectors has a first focus pointsubstantially coincident with a first view region (e.g., the left eye ofan observer), and reflectors in even columns of the array of rotatablereflectors has a second focus point substantially coincident with asecond view region (e.g., the right eye of an observer). Optionally, aframe time period is divided into two time windows, e.g., a first timewindow and a second time window. In the first time window, the firstsub-image is displayed. The second MEM is configured to be in atransmissive optical state to allow the display light passing through.The first MEMS is configured to be in a reflective optical state.Specifically, the reflectors in odd columns of the array of rotatablereflectors in the first MEMS reflects the display light to the left eye(the first view region), and the reflectors in even columns of the arrayof rotatable reflectors in the first MEMS reflects the display light tothe right eye (the second view region). In the second time window, thesecond sub-image is displayed. The second MEM is configured to be in areflective optical state. Specifically, the reflectors in odd columns ofthe array of rotatable reflectors in the second MEMS reflects thedisplay light to the left eye (the first view region), and thereflectors in even columns of the array of rotatable reflectors in thesecond MEMS reflects the display light to the right eye (the second viewregion). When the frame time period corresponding to the frame of imageends, the left eye perceives the sub-images corresponding to the lefteye (e.g., reflected by the odd columns), and the right eye perceivesthe sub-images corresponding to the right eye (e.g., reflected by theeven columns), thereby realizing the naked eye three-dimensionaldisplay.

Numerous alternative embodiments may be practiced to implement the nakedeye three-dimensional display method described herein. For example, thelight modulator assembly may include various numbers and structures ofMEMSs. The tilt angles of the rotatable reflectors of the MEMS invarious embodiments may be determined by experiment and simulation.

In some embodiments, each of the plurality of light modulators has aplate shape. As shown in FIG. 1, each light modulator 21 faces towardsthe image display portion 1, reflecting the display light emitted fromthe image display portion into eyes of an observer. Optionally, a planeof the light modulator 21 forms a tilt angle with the light propagatingdirection. As defined herein, the term “tilt angle” refers to an anglebetween a surface of the light modulator and the light propagatingdirection. Optionally, the tilt angle is an angle between a reflectivesurface of the light modulator and the light propagating direction.Optionally, the light modulator is a liquid crystal panel, and the tiltangle is defined by an angle between a reflective surface of the liquidcrystal panel (e.g., the reflective surface of the second polarizer inthe liquid crystal panel) and the light propagating direction.Optionally, the light modulator is a MEMS, and the tilt angle is definedby an angle between a reflective surface of the MEMS (e.g., thereflective surface of a reflector) and the light propagating direction(as illustrated in FIG. 13).

In some embodiments, the plurality of light modulators has asubstantially the same tilt angle. When the plurality of lightmodulators have a substantially the same tilt angle, the plurality ofsub-images displayed by the plurality of light modulators have asubstantially the same image size, achieving a better display effect. Inthe context of MEMS, when the plurality of light modulators have asubstantially the same tilt angle, not only all reflectors in each MEMShave a substantially the same tilt angle with respect to each other, butall MEMS have a substantially the same tilt angle with respect to eachother. Optionally, each of the plurality of light modulators has a plateshape, and each of the plurality of light modulators has a tilt angle ofapproximately 45 degrees. By having this design, the plurality ofsub-images displayed by the plurality of light modulators have asubstantially the same image size, achieving a better display effect.

In some embodiments, an i-th light modulator is designated to display asub-image; i is an integer, 1≤i≤(N−1); and i=1 for the light modulatormost proximal to the image display portion. Optionally, a side of thei-th light modulator distal to the image display portion is aligned witha side of an (i+1)-th light modulator proximal to the image displayportion, so that the display light passed through the i-th lightmodulator when the i-th light modulator is configured to be in atransmissive optical state is substantially reflected by the (i+1)-thlight modulator when the (i+1)-th light modulator is configured to be ina reflective optical state. Optionally, when viewed along the lightpropagating direction, a projection of the i-th light modulator on the(i+1)-th light modulator substantially overlaps with the (i+1)-th lightmodulator, so that the display light passed through the i-th lightmodulator when the i-th light modulator is in a transmissive opticalstate is substantially received by the (i+1)th light modulator when the(i+1)-th light modulator is configured to be in a reflective opticalstate. By having this design, the plurality of sub-images may besequentially displayed to achieve a better display quality.

For the display light to reach the last light modulator (e.g., the lightmodulator most distal to the image display portion), it has to passthrough the light modulators between the last light modulator and theimage display portion, when the light modulators between the last lightmodulator and the image display portion are configured to be intransmissive optical state. For example, in some embodiments, the lightmodulators are a plurality of liquid crystal panels, the last liquidcrystal panel is configured to be in the reflective optical statewhereas all other liquid crystal panels are configured to be in thetransmissive optical state. Even though the intermediate lightmodulators are configured to be the transmissive optical state, thedisplay light may be partially absorbed when passing through a lightmodulator in transmissive optical state. In some embodiments, brightnessof the light reflected by the last light modulator is enhanced toachieve a more uniform display effect. Optionally, the light modulatormost distal to the image display portion includes a brightness enhancingfilm, e.g., on a side of the light modulator most distal to the imagedisplay portion proximal to the image display portion. Examples of thebrightness enhancing film include NIPOCS PCF series manufactured byNitto Denko Corporation and Vicuiti DBFE series manufactured by Sumitomo3M Ltd.

Similarly, when the display light passes through the first lightmodulator to the (i−1)-th light modulator to reach the i-th lightmodulator, the display light may be partially absorbed when passingthrough the first light modulator to the (i−1)-th light modulator;1≤i≤(N−1); and i=1 for the light modulator most proximal to the imagedisplay portion. In some embodiments, brightness of the light reflectedby the i-th light modulator is enhanced to achieve a more uniformdisplay effect. Optionally, the i-th light modulator includes abrightness enhancing film, e.g., on a side of the i-th light modulatorproximal to the image display portion. For example, the plurality oflight modulators are MEMSs, the brightness enhancing film may bedisposed on the surface of the plurality of rotatable reflectors, e.g.,on a side of the i-th light modulator proximal to the image displayportion.

In another aspect, the present disclosure provides a display systemhaving a display apparatus described herein. In some embodiments, thedisplay system further includes a virtual reality touch controlapparatus coupled to the display apparatus as described herein. In someembodiments, the display system includes other display apparatusescoupled to the display apparatus as described herein for displaysharing.

In another aspect, the present disclosure provides an image displaymethod using a display apparatus as described herein. In someembodiments, the image display method includes separating a frame ofimage into N sub-images; dividing a frame time period into N timewindows corresponding to the N sub-images, respectively, each sub-imageis displayed in each time window; and configuring the N light modulatorsso that a y-th light modulator is in the reflective optical state in ax-th time window, and any light modulator on a side of the y-th lightmodulator proximal to the image display portion is in the transmissiveoptical state; wherein N is an integer≥2; x is an integer, 1≤x≤N; y isan integer, 1≤y≤N; and y=1 for the light modulator most proximal to theimage display portion. Optionally, x=y. Optionally, x is not the same asy.

By having the present image display method, each of the N sub-images maybe displayed in a different time window. For example, when the x-thsub-image is displayed, a light modulator corresponding to the x-thsub-image is configured to be in a reflective optical state, whereas anylight modulator on a side of the light modulator for displaying the x-thsub-image proximal to the image display portion is configured to be in atransmissive optical state. For example, any light modulator in a lightpath between the image display portion and the light modulator fordisplaying the x-th sub-image is configured to be is a transmissiveoptical state so that the display light may pass through from the imagedisplay portion to the light modulator for displaying the x-thsub-image, and the display light is reflected by the light modulator fordisplaying the x-th sub-image to an eye or a view point. Each of the Nsub-images are displayed in a time window. Due to persistence of vision,human eyes can perceive a complete frame of image when a set ofsub-images are displayed in quick succession. Accordingly, in someembodiments, a frame of image may be separated into N sub-images along awidth direction of the frame of image. As a result, image display of acomplete frame of image may be achieved by using an image displayportion having a width corresponding to only a width of one sub-image(rather than the width of an entire frame of image). By having thisdesign, the thickness of the image display portion may be reduced,resulting in a miniaturized display apparatus.

In some embodiments, the step of separating the frame of image into Nsub-images includes separating the frame of image into N sub-imagesalong a width direction of the frame of image. In some embodiments, thestep of separating the frame of image into N sub-images includesseparating the frame of image into a first sub-image corresponding to afirst view region (e.g., a first view point) and a second sub-imagecorresponding to a second view region (e.g., a second view point). Insome embodiments, the step of separating the frame of image into Nsub-images includes separating the frame of image into N portions alonga width direction of the frame of image; and further separating each ofthe N portion into a first sub-image corresponding to a first viewregion (e.g., a first view point) and a second sub-image correspondingto a second view region (e.g., a second view point).

In some embodiments, a frame of image is separated into N sub-images,and a frame time period is divided into N time windows corresponding tothe N sub-images, respectively. FIG. 14 is a diagram illustratingseparation of a frame of image into multiple sub-images in someembodiments. Referring to FIG. 14, a frame of image is separated intoseven sub-images.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image.Optionally, the 1^(st) to N-th sub-images are sequentially displayed in1^(st) to N-th time windows. Optionally, the N-th to 1^(st) sub-imagesare sequentially displayed in 1^(st) to N-th time windows. FIG. 15 is adiagram illustrating a displaying sequence of multiple sub-images insome embodiments. Referring to FIG. 15, a frame of image is separatedinto seven sub-images, the sub-image 1 is the first sub-image to bedisplayed. As shown in FIG. 15, seven sub-images 1 to 7 are sequentiallydisplay along the width direction of the frame of image in the first toseventh time windows. FIG. 16 is a diagram illustrating a displayingsequence of multiple sub-images in some embodiments. Referring to FIG.16, a frame of image is separated into seven sub-images, the sub-image 7is the first sub-image to be displayed. As shown in FIG. 16, sevensub-images 7 to 1 are sequentially display along the width direction ofthe frame of image in the first to seventh time windows.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image; afirst group of the N sub-images are displayed before a second group ofthe N sub-images; the first group and the second group being differentgroups selected from a group of odd-numbered sub-images and a group ofeven-numbered sub-images. FIG. 17 is a diagram illustrating a displayingsequence of multiple sub-images in some embodiments. Referring to FIG.17, a frame of image is separated into seven sub-images, the sub-image 1is the first sub-image to be displayed. As shown in FIG. 17, theodd-numbered sub-images 1, 3, 5, and 7 are first sequentially displayedin the first to fourth time windows, the even-numbered sub-images 2, 4,and 6 are then sequentially displayed in the fifth to seventh timewindows. FIG. 18 is a diagram illustrating a displaying sequence ofmultiple sub-images in some embodiments. Referring to FIG. 18, a frameof image is separated into seven sub-images, the sub-image 2 is thefirst sub-image to be displayed. As shown in FIG. 18, the even-numberedsub-images 2, 4, and 6 are first sequentially displayed in the first tothird time windows, the odd-numbered sub-images 1, 3, 5, and 7 are thensequentially displayed in the fourth to seventh time windows.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image; Nis an even number; the N sub-images are displayed in an order of the1^(st) sub-image, the N-th sub-image, (N/2)-th sub-image, a sub-imagebetween the 1^(st) sub-image and the (N/2)-th sub-image, a sub-imagebetween the (N/2)-th sub-image and the N-th sub-image, until allsub-images are displayed in 1^(st) to N-th time windows. FIG. 19 is adiagram illustrating a displaying sequence of multiple sub-images insome embodiments. Referring to FIG. 19, a frame of image is separatedinto six sub-images, the sub-image 1 is the first sub-image to bedisplayed. As shown in FIG. 19, the six sub-images are displayed in anorder of the first sub-image, the sixth sub-image, the third sub-image,the second sub-image, the fourth sub-image, and the fifth sub-image inthe first to the sixth time windows.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image; Nis an odd number; the N sub-images are sequentially displayed in anorder of the 1^(st) sub-image, the N-th sub-image, ((N+1)/2)-thsub-image, a sub-image between the 1^(st) sub-image and the ((N+1)/2)-thsub-image, a sub-image between the ((N+1)/2)-th sub-image and the N-thsub-image, until all sub-images are displayed in 1^(st) to N-th timewindows. FIG. 20 is a diagram illustrating a displaying sequence ofmultiple sub-images in some embodiments. Referring to FIG. 20, a frameof image is separated into seven sub-images, the sub-image 1 is thefirst sub-image to be displayed. As shown in FIG. 20, the sevensub-images are displayed in an order of the first sub-image, the seventhsub-image, the fourth sub-image, the second sub-image, the fifthsub-image, the third sub-image, and the sixth sub-image in the first tothe seventh time windows.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image; Nis an even number; the N sub-images are sequentially displayed in anorder of (N/2)-th sub-image, the 1^(st) sub-image, the N-th sub-image, asub-image between the 1^(st) sub-image and the (N/2)-th sub-image, asub-image between the (N/2)-th sub-image and the N-th sub-image, untilall sub-images are displayed in 1^(st) to N-th time windows. FIG. 21 isa diagram illustrating a displaying sequence of multiple sub-images insome embodiments. Referring to FIG. 21, a frame of image is separatedinto six sub-images, the sub-image 3 is the first sub-image to bedisplayed. As shown in FIG. 21, the six sub-images are displayed in anorder of the third sub-image, the first sub-image, the sixth sub-image,the second sub-image, the fourth sub-image, and the fifth sub-image inthe first to the sixth time windows.

In some embodiments, the N sub-images include 1^(st) to N-th sub-imagessequential arranged along the width direction of the frame of image; Nis an odd number; the N sub-images are sequentially displayed in anorder of ((N+1)/2)-th sub-image, the 1^(st) sub-image, the N-thsub-image, a sub-image between the 1^(st) sub-image and the ((N+1)/2)-thsub-image, a sub-image between the ((N+1)/2)-th sub-image and the N-thsub-image, until all sub-images are displayed in 1^(st) to N-th timewindows. FIG. 22 is a diagram illustrating a displaying sequence ofmultiple sub-images in some embodiments. Referring to FIG. 22, a frameof image is separated into seven sub-images, the sub-image 4 is thefirst sub-image to be displayed. As shown in FIG. 22, the sevensub-images are displayed in an order of the fourth sub-image, the firstsub-image, the seventh sub-image, the second sub-image, the fifthsub-image, the third sub-image, and the sixth sub-image in the first tothe seventh time windows.

In some embodiments, the step of configuring the N light modulatorsincludes configuring the N light modulator so that the y-th lightmodulator is in the reflective optical state when a j-th sub-image isdisplayed in the x-th time window, y equals to N−j+1, j is an integer,and 1≤j≤N. The relationship between y and x may be determined accordingto a sequential displaying order as described herein. By having thisdesign, the plurality of light modulators may display the plurality ofsub-images according to their original spatial order along the widthdirection of the frame of image, even though the temporal order ofdisplaying the plurality of sub-images is different from the originalspatial order. For example, the first sub-image along the widthdirection of the frame of image is displayed by the N-th lightmodulator, the second sub-image along the width direction of the frameof image is displayed by the (N−1)-th light modulator, the (N−1)-thsub-image along the width direction of the frame of image is displayedby the first light modulator, the N-th sub-image along the widthdirection of the frame of image is displayed by the first lightmodulator, and so on, i.e., y equals to N−j+1. In this manner, the imageperceived by an observer corresponds to the original image provided bythe image display portion.

Thus, in some embodiments, the plurality of sub-images are sequentiallydisplayed intervals as described herein. Even though during a certaintime window, not all sub-images are displayed, an observer may stillperceive a complete frame of image due to persistence of vision when aset of sub-images are displayed in quick succession.

In some embodiments, the N light modulators include N liquid crystalpanels, each of the N liquid crystal panels includes a first polarizer,a first transparent electrode, a liquid crystal layer, a secondtransparent electrode and a second polarizer laminated in order; thesecond polarizer is a reflective polarizer disposed on a side of thefirst polarizer distal to the image display portion. Optionally, thestep of configuring the N light modulators includes controlling anelectric field between the first transparent electrode and the secondtransparent electrode.

In some embodiments, the first polarizer has a first transmission axis,the second polarizer has a second transmission axis, the firsttransmission axis being substantially perpendicular to the secondtransmission axis. A direction of a long axis of liquid crystalmolecules in the liquid crystal layer is spirally twisted byapproximately 90 degrees between the first transparent electrode and thesecond transparent electrode when electric field is not applied. Whenelectric field is not applied, a direction of a long axis of liquidcrystal molecules proximal to the first transparent electrode issubstantially parallel to the first transmission axis, and a directionof a long axis of liquid crystal molecules proximal to the secondtransparent electrode is substantially parallel to the secondtransmission axis. Each of the N liquid crystal panels is in thereflective optical state when there is no electric field between thefirst transparent electrode and the second transparent electrode. Eachof the N liquid crystal panels is in the transmissive optical state whena strength of the electric field is larger than a threshold value.

In some embodiments, the first polarizer has a first transmission axis,the second polarizer has a second transmission axis, the firsttransmission axis being substantially parallel to the secondtransmission axis. A long axis of liquid crystal molecules in the liquidcrystal layer is substantially parallel to the first transmission axisand the second transmission axis.

In some embodiments, the N light modulators include N MEMSs, and each ofthe N MEMSs includes a plurality of rotatable reflectors. Optionally,the step of configuring the N light modulators includes rotating theplurality of rotatable reflectors of a MEMS to change tilt angles of theplurality of rotatable reflectors.

In some embodiments, the plurality of rotatable reflectors of the MEMSare rotated to have a substantially the same tilt angle with respect tothe light propagating direction so that the MEMS is in the reflectiveoptical state. The display light reflected by the plurality of rotatablereflectors has a substantially the same propagating direction.

In some embodiments, the light modulator assembly includes a pluralityof MEMSs. A plurality of rotatable reflectors of at least a first one ofthe plurality of MEMSs are rotated to have a first light focus pointsubstantially coincident with a first view region. A plurality ofrotatable reflectors of at least a second one of the plurality of MEMSsare rotated to have a second light focus point substantially coincidentwith a second view region. The second view region being different fromthe first view region.

In some embodiments, the light modulator assembly includes a pluralityof MEMSs, and each of the plurality of MEMSs includes an array ofrotatable reflectors corresponding to an array of pixels in the imagedisplay portion. Reflectors in odd columns of the array of rotatablereflectors are rotated to have a first light focus point substantiallycoincident with a first view region; and reflectors in even columns ofthe array of rotatable reflectors are rotated to have a second lightfocus point substantially coincident with a second view region. Thesecond view region being different from the first view region.

In some embodiments, the image display method further includes enhancingbrightness of at least one of the N sub-images so that sub-imagesdisplayed in light modulators distal to the image display portion have ahigher brightness than sub-images displayed in light modulators proximalto the image display portion.

The foregoing description of the embodiments of the invention has beenpresented for purposes of illustration and description. It is notintended to be exhaustive or to limit the invention to the precise formor to exemplary embodiments disclosed. Accordingly, the foregoingdescription should be regarded as illustrative rather than restrictive.Obviously, many modifications and variations will be apparent topractitioners skilled in this art. The embodiments are chosen anddescribed in order to explain the principles of the invention and itsbest mode practical application, thereby to enable persons skilled inthe art to understand the invention for various embodiments and withvarious modifications as are suited to the particular use orimplementation contemplated. It is intended that the scope of theinvention be defined by the claims appended hereto and their equivalentsin which all terms are meant in their broadest reasonable sense unlessotherwise indicated. Therefore, the term “the invention”, “the presentinvention” or the like does not necessarily limit the claim scope to aspecific embodiment, and the reference to exemplary embodiments of theinvention does not imply a limitation on the invention, and no suchlimitation is to be inferred. The invention is limited only by thespirit and scope of the appended claims. Moreover, these claims mayrefer to use “first”, “second”, etc. following with noun or element.Such terms should be understood as a nomenclature and should not beconstrued as giving the limitation on the number of the elementsmodified by such nomenclature unless specific number has been given. Anyadvantages and benefits described may not apply to all embodiments ofthe invention. It should be appreciated that variations may be made inthe embodiments described by persons skilled in the art withoutdeparting from the scope of the present invention as defined by thefollowing claims. Moreover, no element and component in the presentdisclosure is intended to be dedicated to the public regardless ofwhether the element or component is explicitly recited in the followingclaims.

What is claimed is:
 1. A display apparatus, comprising: an image display portion for displaying an image, the image display portion emitting display light along a light propagating direction; and a light modulator assembly comprising a first light modulator and a second light modulator arranged in series along the light propagating direction; the second light modulator having at least a reflective optical state; and the first light modulator being switchable between the reflective optical state and a transmissive optical state and being on a side of the second light modulator proximal to the image display portion; a total number of light modulators including the second light modulator and any light modulator on a side of the second light modulator proximal to the image display portion is N, N is an integer≥2; wherein the N light modulators comprise N micro-electromechanical systems (MEMSs), each of the N MEMSs comprises a plurality of rotatable reflectors.
 2. The display apparatus of claim 1, wherein the plurality of rotatable reflectors of a MEMS have a substantially the same tilt angle with respect to the light propagating direction when the MEMS is in the reflective optical state.
 3. The display apparatus of claim 1, wherein the light modulator assembly comprises a plurality of MEMSs, at least a first one of the plurality of MEMSs has a first light focus point substantially coincident with a first view region; and at least a second one of the plurality of MEMSs has a second light focus point substantially coincident with a second view region; the second view region being different from the first view region.
 4. The display apparatus of claim 1, wherein the light modulator assembly comprises a plurality of MEMSs, each of the plurality of MEMSs comprises an array of rotatable reflectors corresponding to an array of pixels in the image display portion; reflectors in odd columns of the array of rotatable reflectors has a first light focus point substantially coincident with a first view region; and reflectors in even columns of the array of rotatable reflectors has a second light focus point substantially coincident with a second view region; the second view region being different from the first view region.
 5. An image display method using a display apparatus of claim 1, comprising: separating a frame of image into N sub-images; dividing a frame time period into N time windows corresponding to the N sub-images, respectively; and configuring the N light modulators so that a y-th light modulator is in the reflective optical state in a x-th time window, and any light modulator on a side of the y-th light modulator proximal to the image display portion is in the transmissive optical state; wherein N is an integer≥2; x is an integer, 1≤x≤N; y is an integer, 1≤y≤N; and y=1 for the light modulator most proximal to the image display portion.
 6. The method of claim 5, wherein the light modulator assembly is configured so that substantially no more than one light modulator reflects the display light at a time.
 7. The method of claim 5, wherein the step of separating the frame of image into N sub-images comprises separating the frame of image into N sub-images along a width direction of the frame of image.
 8. The method of claim 5, wherein the step of separating the frame of image into N sub-images comprises separating the frame of image into a first sub-image corresponding to a first view region and a second sub-image corresponding to a second view region.
 9. The method of claim 5, wherein the step of separating the frame of image into N sub-images comprises separating the frame of image into N portions along a width direction of the frame of image; and further separating each of the N portions into a first sub-image corresponding to a first view region and a second sub-image corresponding to a second view region.
 10. The method of claim 7, wherein the step of configuring the N light modulators comprises configuring the N light modulator so that the y-th light modulator is in the reflective optical state when a j-th sub-image is displayed in the x-th time window, y equals to N−j+1, j is an integer, and 1≤j≤N.
 11. The method of claim 5, wherein the step of configuring the N light modulators comprises rotating the plurality of rotatable reflectors of a MEMS to change tilt angles of the plurality of rotatable reflectors.
 12. The method of claim 11, wherein the plurality of rotatable reflectors of the MEMS are rotated to have a substantially the same tilt angle with respect to the light propagating direction so that the MEMS is in the reflective optical state; the display light reflected by the plurality of rotatable reflectors has a substantially the same propagating direction.
 13. The method of claim 11, wherein the light modulator assembly comprises a plurality of MEMSs, a plurality of rotatable reflectors of at least a first one of the plurality of MEMSs are rotated to have a first light focus point substantially coincident with a first view region; and a plurality of rotatable reflectors of at least a second one of the plurality of MEMSs are rotated to have a second light focus point substantially coincident with a second view region; the second view region being different from the first view region.
 14. The method of claim 11, wherein the light modulator assembly comprises a plurality of MEMSs, each of the plurality of MEMSs comprises an array of rotatable reflectors corresponding to an array of pixels in the image display portion; reflectors in odd columns of the array of rotatable reflectors are rotated to have a first light focus point substantially coincident with a first view region; and reflectors in even columns of the array of rotatable reflectors are rotated to have a second light focus point substantially coincident with a second view region; the second view region being different from the first view region.
 15. The method of claim 5, further comprising enhancing brightness of at least one of the N sub-images so that sub-images displayed in light modulators distal to the image display portion have a higher brightness than sub-images displayed in light modulators proximal to the image display portion. 